hello dear friends
i want to know that what is diffrent between a 2-D circular pipe and a two-parallel plate channel to simulating in fluent
thanks alot

In case of 2-D circular pipe, you're going to model a 3-D pipe flow by implementing "axis" B.C. But when you have parallel plates, the flow is completely 2-D and there is no normal velocity gradient on the plane. In other words, you are modeling flow between a couple infinitely wide plates.

In case of 2-D circular pipe, you're going to model a 3-D pipe flow by implementing "axis" B.C. But when you have parallel plates, the flow is completely 2-D and there is no normal velocity gradient on the plane. In other words, you are modeling flow between a couple infinitely wide plates.